7000 Volts DC

[RH77]

After 9 years of faithful, continuous service, my HEPA filter fan finally died. It filtered it's last particle of allergens. Services will be held Tuesday.

I never used it, but it came with an "Air Ionizer" feature -- basically a series of prongs that negatively charge the outgoing air (with the idea of making particles stick to the filter media easier). The downside is heavy-duty dust sticking to the room's surfaces -- so it was never used (plus the idea of air pollution).

In an effort to repair the motor that gave out, I dismantled the unit...

Caution: Do not attempt: high voltage equipment inside.

Disassembling the unit showed the failing motor, and an interesting inverter Input: 120VAC, Output: 7000VDC-Negative. Precautions were made to ensure full discharge before removal.

Is there a practical use for this kind of high-voltage device? I got the motor working again, but the brushes are toast, so the whole thing is doomed for recycling.


RH77

[JohnnyGrey]

I believe that you can use the voltage to create a solid state fan, one with no moving parts. Also, if you reverse the electrodes, you can make the dust stick to a piece of metal, like the Ionic Breeze, right?

[LostCause]

I'm pretty sure that voltage is for the electrostatic precipitator.

Air has a resistance of around 10kvolts/cm. Tasers and TIG welders use high voltage to strike arcs across large distances. I'm assuming the electrostatic precipitator used that voltage to increase its range.

High voltage, low current devices generally aren't lethal. You could use that powersupply to build an electric fence. If you can figure out how to bump up the voltage further, you can build yourself a Jacob's Ladder and ecomod like an evil scientist.



- LostCause

[JohnnyGrey]

How low is low current? You'd be surprised how little it takes to stop your heart.

Also, I'm pretty sure for any sustained arc like a Jacob's ladder, you need AC. Be careful with these though, they generate Ozone which IIRC, is even more poisonous than carbon monoxide. Headache and nausea aren't unusual. It has a sweet burning electronics smell. Kind of like brushes on a high powered DC motor.

[LostCause]

I have no idea what wattage will kill a person, but I remember watching my old welding teacher strike a TIG arc on his finger and hold it there for over a minute. Then again, I've also heard of people lighting on fire from touching high voltage power lines. I guess there's some wiggle room.

I also suspect the lethality of electricity to be dependent on the person and their luck. I'm bet some people have died from touching mains power while others have survived touching overhead powerlines. In any case, you won't find me taking the chance.

The first place I ever saw a Jacob's Ladder was at the old LA Science Museum, so I'm assuming it's relatively safe. Given adequate ventilation, I doubt the ozone would be much of a concern. It is something worth considering, though.

- LostCause

[RH77]

Originally Posted by JohnnyGrey

Also, if you reverse the electrodes, you can make the dust stick to a piece of metal, like the Ionic Breeze, right?

Basically, the device has 120 VAC in (2-wires: neutral and hot), and one neutral DC wire as the output. If the 2 input wires are reversed, could the dust-plate work or likely short-out the works?

Originally Posted by JohnnyGrey

How low is low current? You'd be surprised how little it takes to stop your heart.

All of us have likely been shocked at 30,000 Volts: Static Electricity. Where it gets deadly is the Amperage and location of current travel through the body. My EMT/Fire classes (ages ago) focused more on the treatment and safety rather than the cause. The mechanism of electric shock generally causes the muscles to tense up in appendages, and with the hand especially, grasp the source more tightly. Rule #1 was to not become a victim yourself, so often it was a helpless venture to aid in getting someone away from the shock source. Most of the time the power had been cut and then treatment began. Usually 2 burn marks for high Amp stuff. Then there's the heart defibrillator. One Medic didn't take the "Clear" announcement seriously and had a hand on the stretcher during a shock. Knocked him on his arse. He was really lucky -- I think it was up to 360 Joules on that one.

To me, the most annoying (usually) non-lethal shocks are in-house residential telephone lines. I spent a summer installing Ethernet cable that usually shared a splice terminal with that zap of Ma Bell nearby.

Anyways, too bad it can't be used as some crazy add-on to negatively charge fuel particles or something for amazing FE!

RH77